1. Field of the Invention
This invention relates to an improvement in a two-cylinder V-type spark-ignition engine, generally called a V-2 engine.
2. Description of the Related Art
various V-2 engines are known and one example of such known V-2 engines is disclosed in Japanese Patent Laid-open Publication No. HEI-2-33415. The disclosed engine is of the vertical type having a crankshaft extending vertically with two cylinders mounted to a crankcase being arranged at an angle to each other in a horizontal plane. The engine is installed in the body of an automotive lawn mower in such a manner that respective tops of the cylinders are directed toward the forward direction of the automotive lawn mower.
Since the two cylinders of the known V-2 engine are arranged symmetrically with respect to the longitudinal axis of the automotive lawn mower, the maximum width of the engine (i.e., the distance between the light-hand end of a head cover of the left cylinder and the right-hand end of a head cover of the right cylinder) is relatively large. The V-2 engine having such a relatively large maximum width gives rise to a problem when installed in a vehicle having a limited width.
In a motorized working machine such as automotive lawn mower, it may occur that the existing engine, namely, an engine currently installed in the vehicle is replaced by another engine of different power or displacement in order to cope with a change in the working load. For instance, a single cylinder engine is replaced with a v-2 engine or vise versa on the same vehicle body. Accordingly, for the V-2 engine, it is desirable to reduce the size to an extent which is comparable to the size of the single cylinder engine. Since the overall size of the V-2 engine is determined by the width, that is, the outside distance between the two cylinder blocks, efforts for downsizing the V-2 engine are essentially focused on reduction of the width.
It is accordingly an object of the present invention to provide a compact V-2 engine having an arrangement which is capable of reducing the maximus size in the direction of width of the V-2 engine.
According to the present invention, there is provided a V-2 engine comprising: a crankshaft rotatably supported in a crankcase, the crankcase having a centerline passing through the axis of the crankshaft; two cylinder blocks each having one head cover and mounted to the crankcase such that the respective cylinder axes of the cylinder blocks extend at an angle to each other and merge together at the axis of the crankshaft, with the angle formed between the cylinder axes being divided into two angle parts by the centerline of the crankcase; and an auxiliary machine mounted to the crankcase on the same side as one of the cylinder blocks when viewed from the axis of the crankshaft. The cylinder blocks are offset from a symmetric position with respect to the centerline of the crankcase to such an extent that a straight line circumscribing an outer end of the head cover of the one cylinder block and an outer end of the auxiliary machine is in parallel to the centerline of the crankcase.
By thus offsetting the cylinder blocks from the symmetric position with respect to the centerline of the crankcase, the maximum width of the V-2 engine as measured in a direction perpendicular to the crankcase centerline becomes smaller than that of a conventional V-2 engine with cylinder blocks arranged symmetrically with respect to the crankcase centerline. The V-2 engine having a reduced maximum width requires less space for installation than the conventional V-2 engine and, hence, can reduce the overall size of a machine or equipment in which the engine is installed.
The above and other object, features and advantages of the present invention will become manifest to those versed in the art upon making reference to the following description and accompanying sheets of drawings in which a preferred structural embodiment incorporating the principle of the invention is shown by way of illustrative example.